Electrical switchgear comprising several housing parts

ABSTRACT

A switching chamber enclosure includes a number of enclosure parts with specific functional subdivision, in which switching elements are arranged. The enclosure of the switching device is formed at least by one lower shell and one upper shell, which are separated from one another by a horizontal separating joint. In addition, one or more intermediate shells may provided, which are likewise separated from the lower shell, from the upper shell and from one another by horizontal separating joints.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/DE00/04201 which has an Internationalfiling date of Nov. 20, 2000, which designated the United States ofAmerica, the entire contents of which are hereby incorporated byreference.

FIELD OF THE INVENTION

The invention generally relates to the field of electrical switchingdevices, and more preferably relates to ones which have at least oneswitching contact system which can be operated via an actuating shaftand even more preferably relates to ones whose contact surfaces runessentially parallel to a predetermined plane. It is preferablyapplicable to the design configuration of a switching chamber enclosurewhich holds the switching contact system and further switch parts, andwhich includes at least two enclosure parts.

BACKGROUND OF THE INVENTION

In one known electrical switching device in the form of a low-voltagecircuit breaker, the switching chamber enclosure includes a front and arearward enclosure part. Each have a circumferentially closed surfaceand absorb mechanical forces that occur during operation of the moveableswitching contact. These forces act essentially at right angles to thecontact surfaces of the switching contact system. In the normal way forlow-voltage circuit breakers, the two enclosure parts rest against oneanother along a separating joint. The joint runs parallel to the axis ofthe switching shaft. When the switching device is in the in-useposition, it runs vertically between the enclosure front wall and theenclosure rear wall.

Since one contact is associated with the front enclosure part and theother contact is associated with the rearward enclosure part, thisarrangement requires that the enclosure parts be aligned correctly withone another, such that they match. This arrangement of the contacts alsomeans that the forces which are associated with the switching processesand which run at right angles to the contact surfaces of the switchingcontacts act on the enclosure parts at right angles to the separatingjoint. Generally, this means that the enclosure parts must be heldtogether using tie rods (U.S. Pat. No. 4,764,650). Furthermore, aconfiguration of the switching chamber enclosure such as this makes itnecessary to remove the rear wall, in order to gain access to theappropriate assemblies, for the purpose of maintenance or repair of theswitching contact systems. Once the appropriate work has been carriedout, the front wall and the rear wall must be joined together onceagain.

With a conventional construction, an enclosure part which is stressed insuch a way is subject to mutual alignment via the tie rods via aconstriction in the through-holes. When tie rods such as these are used,this results in considerable difficulties in the production of theenclosure parts and of the stamping tools which are required for theirproduction.

Firstly, the manufacturing processes are subject to tight tolerances.Secondly, it is possible for problems to occur during assembly as aresult of screws becoming jammed, since the through-holes are formed byrelatively long and thus unstable pins in the stamping tool. These pinscan be elastically deformed by the stamping force and by thedisplacement of the substance being molded, as a result of which thethrough-holes for the tie rods may be misaligned.

In another known low-voltage circuit breaker, an additional element isused to reinforce the connection between the enclosure parts. Thiselement, which is in the form of a dovetail, is arranged between theenclosure parts and extends along the side walls of the enclosure partswithin a channel, which is formed by the two enclosure parts, in orderto hold the element. This element is used to increase the strength ofthe connection between the enclosure parts with regard to forcetransmission, but contributes to mutual alignment of the enclosure partsat most in one plane, namely the horizontal. It also uses a relativelylarge amount of material and results in additional assembly effort (U.S.Pat. No. 4,899,253).

SUMMARY OF THE INVENTION

An embodiment of the invention is based on an object of reducing thedesign complexity for coping with the mechanical forces which occurduring switching processes, and hence of reducing the assembly effort.

According to an embodiment of the invention, this object is achieved bythe separating joint between those housing parts, which are in each caseto be joined together, running at right angles to the predeterminedplane. This measure improves, for example, the enclosure strength in thedirection in which the forces act, such that there is no need to use tierods to hold the enclosure parts together.

Interlocking alignment arrangements may be provided on the enclosureparts to be joined together, for mutual positive alignment (centering)of the enclosure parts.

The enclosure parts may have teeth on the separating joints.

The interlocking alignment arrangements are expediently arranged on theouter walls of the enclosure parts, or at other suitable points, forexample on phase partition walls. This is necessary in particular inlarge switching devices, such as circuit breakers with single-poleopening, which have a coupling bolt for each pole, in order to securethe coupling bolts axially. The interlocking alignment arrangements mayadvantageously be in the form of integrally formed lugs on one of thetwo enclosure parts to be joined together, or in the form of recessesfor holding the lugs in the other of the enclosure parts to be joinedtogether. Owing to the integrally formed lugs on one enclosure part andthe cutouts in the other enclosure part, through-windows can still beprovided after the lugs start to engage in the cutouts. That is, theycan be provided when the enclosure shells are already aligned with oneanother, but before they have been joined together completely.

The positions and the sizes of the interlocking alignment arrangementscan be advantageously chosen such that further switch parts. Inparticular connecting parts, can still be installed before the enclosureparts are finally joined together, in a position in which the switchparts which are already installed on these enclosure parts are alsoalready aligned with one another.

In the case of low-voltage circuit breakers, for example, it isexpedient for at least one integrally formed alignment arrangement to bepositioned and to be of such a size that, in the state described above,shafts or other connecting parts, for example one or more coupling boltsbetween the contact and the drive, can be inserted which are fixed atthe side by the lugs of the interlocking alignment arrangements. This ispreferably done once the enclosure parts have been joined togethercompletely. This ensures that the corresponding part, for example acoupling bolt, is secured axially without any further securing elementssince, as mentioned above, alignment arrangements may also be providedin the phase partition walls, if this is necessary.

An arcing chamber, possibly a switching gas damper and an arcing chambercover are advantageously integrated in one enclosure part. Inconsequence, no special parts are required for this purpose. Theswitching gas is ejected through the enclosure part at the end.

In order to make it possible for the cables between sensors and anovercurrent release not to run across an enclosure separation, theseitems may be provided within one enclosure shell, with a mounting platefor the auxiliary releases being integrated in one enclosure shell, forthis purpose. This makes it possible to avoid damage to the connectingcables as can occur in known switching chamber enclosures when, forexample, the rear wall is removed for maintenance or repair purposes.

Bearing shells for the actuating shaft are advantageously integrated inthe enclosure walls of the enclosure parts. This makes it possible tosave additional components for the bearings for the switching shaft.

Outlet openings, through which connecting rails of the switching deviceare passed, are advantageously provided in the separating joints. Thisarrangement results in an additional alignment effect on the enclosureparts, by means of the side walls of the outlet openings with theinserted connecting rails, when the enclosure shells are being joinedtogether.

BRIEF DESCRIPTION OF THE DRAWINGS

To assist understanding, the invention will be explained in more detailin the following text using a preferred example, which does not restrictthe scope of protection of the invention, and with reference to theassociated drawings, wherein

FIG. 1 shows, schematically, a perspective view of the front face of aswitching chamber enclosure according to an embodiment of the inventionfor holding a switching contact system of an electrical switchingdevice, for example a low-voltage circuit breaker, seen from the frontright-hand side.

FIG. 2 shows, schematically, a perspective view of the rear face of theswitching chamber enclosure shown in FIG. 1, seen from the rearleft-hand side.

FIG. 3 schematically shows a sectional view of the switching chamberenclosure depicted in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to FIG. 1, the switching chamber enclosure includes a numberof enclosure parts, namely a lower shell 2, an upper shell 3 and anintermediate shell 4, which are separated from one another by means ofhorizontal separating joints 5; 6.

Attachment holes 7 are provided on the front face of the switchingchamber enclosure 1 for a switch drive (which is not illustrated), and athrough-opening 8 is provided for a switching linkage, which is likewisenot illustrated.

For correct matched alignment (centering) of the individual enclosureparts, the lower shell 2, the upper shell 3 and the intermediate shell 4are provided with alignment arrangements 9 on the separating joints 5;6, such that, when the enclosure parts are being joined together, theswitch parts to be assembled are also aligned with one another.

The interlocking alignment arrangements 9 are in the form of integrallyformed lugs 10 on the two sides (one side cannot be seen) in theseparating joint 5 on the upper shell 3, and are in the form of recesses11 for holding the said lugs 10, in the intermediate shell 4. Integrallyformed lugs 13 (one side cannot be seen) on the intermediate shell 4 areprovided in the separating joint 6, and recesses 14 for holding theintegrally formed lugs 13 are provided on the lower shell 2. Blowingopenings 12 of an arcing chamber, which is arranged such that it isintegrated on the upper shell 3, emerge from the upper shell 3 at thetop.

Bearing shells 15 for an actuating shaft are integrated in the enclosurewalls, in the separating joint 5 between the upper shell 3 and theintermediate shell 4. This makes it possible to save additionalcomponents for the bearings for the actuating shaft.

As shown in FIG. 2, in which the already explained enclosure parts areprovided with the same reference symbols as in FIG. 1, outlet openings18, 19, which are arranged in the separating joints, together with theupper and lower connecting rails 16; 17 which emerge there exert anadditional alignment effect on the enclosure shells 2; 3; 4.

According to FIG. 3, the switching chamber housing 1 comprises aswitching-contact system 20 and additional switch parts, such as thelight-arc quenching chamber 21, the switching gas damper 22, sensors 23,the cable guide 24, the auxiliary triggers 25, 26, the excess currenttrigger 27 and the switching shaft 28.

The switching shaft 28 functions in the known manner for actuating theswitching contact system 20, for which the contact surfaces 29, 30essentially run parallel to a predetermined plane 31. The three housingparts 2, 3, 4 of switching chamber housing 1, which absorb themechanical forces that are generated in approximately perpendiculardirection to the contact surfaces 29, 30 during the actuation of theswitching contact system 20, fit against each other along the separatingjoints 5, 6. The separating joints 5, 6 in this case extend parallel tothe switching shaft 28 axis and perpendicular to the predetermined plane31. FIG. 3 furthermore shows the switching rod assembly 32, whichextends through the openings 8 for the embodiment shown in FIG. 1, aswell as the switching drive 33 that is attached to the front of theswitching chamber housing via the fastening holes 7, also shown in FIG.1.

The solution according to an embodiment of the invention has at leastone of the following advantages:

Improvement in the housing strength in the direction in which force isapplied by the action of force from contact force springs andshort-circuit loads. The tie rods for holding the front wall and rearwall together are no longer used to absorb forces, as was previouslynormal. In this embodiment, the forces occur in one and the same partand are absorbed by this part, without any joint whatsoever needing tobe bridged by elements such as tie rods to absorb forces. This meansthat those forces which were previously exerted on the enclosure parts,such as the front and rear walls of the low-voltage circuit breaker, andwhich attempted to force them apart, are now intrinsically absorbed bythe enclosure shell.

The positioning of the actuating shaft in the separating joint betweentwo enclosure shells arranged one above the other, and the integrationof the bearing shells in them, means that there is no longer any needfor separate bearing elements.

The assembly time during manufacture is minimized. During assembly ofthe switch, the lower connecting rails together with the moveablecontacts can be inserted into the lower shell from underneath. Theaccessibility of the coupling point from above allows simple coupling tothe exposed actuating shaft. This means simple, uncomplicated access toparts which may be subject to wear. The upper connecting rail isinstalled in the upper shell.

The tolerances for auxiliary contacts for control and signaling purposesare minimized. Relevant, associated and interacting parts are allarranged in one enclosure part; in consequence, there are no tolerancesresulting from the assembly of the enclosure parts.

The fact that the arcing chambers are inserted into the upper shellmeans that the switching contacts can easily be maintained simply bylifting off the upper shell, since they arc easily visible and are in anopen position once the upper shell has been removed.

The integrated arcing chamber cover reduces the complexity forconnection. There are no gaps to be secured by complex labyrinths. Theblowing cover is a component of the upper shell, and there are no jointsthat need to be sealed.

It is even possible to provide channels, for the cables from the sensorsto the overcurrent releases and display instruments, while the enclosureparts are being manufactured. The cables cannot be damaged. No measures,such as a rear wall attached by hinges, are required in order to avoiddamage (tearing off) to the sensitive power cables between the currenttransformers and the overcurrent releases, which are located at thefront.

The switching chamber enclosure can be disassembled, without anyproblems, for repair and maintenance work.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. A switching chamber enclosure for holding at least one switchingcontact system and switch parts for an electrical switching device,wherein an actuating shaft is provided for operation of the at least oneswitching contact system, and wherein contact surfaces of the at leastone switching contact system run essentially parallel to a predeterminedplane, the switching chamber enclosure comprising: at least twoenclosure parts resting against one another along a separating jointthat, extends parallel to the axis of the actuating shaft, so that theenclosure parts absorb mechanical forces occurring during operation ofthe at least one switching contact system, extends approximately atright angles to the contact surfaces, and extends at right angles to thepredetermined plane.
 2. The switching chamber enclosure as claimed inclaim 1, wherein interlocking alignment arrangements are provided on theenclosure parts for mutual positive alignment of the enclosure parts. 3.The switching chamber enclosure as claimed in claim 2, wherein theinterlocking alignment arrangements are in the form of integrally formedlugs on at least one of the enclosure parts, and are in the form ofrecesses, for holding the lugs, in at least one other of the enclosureparts.
 4. The switching chamber enclosure as claimed in claim 1, whereinan arcing chamber, a switching gas damper and an arcing chamber coverare integrated in at least one enclosure part.
 5. The switching chamberenclosure as claimed in claim 1, wherein bearing shells for theactuating shaft are integrated in the enclosure walls of at least one ofthe enclosure parts.
 6. The switching chamber enclosure as claimed inclaim 1, wherein outlet openings are provided in the separating jointfor connecting rails to be passed out.
 7. The switching chamberenclosure as claimed in claim 1, wherein at least two enclosure partsare provided at ends of the switching chamber enclosure and at least oneintermediate enclosure part is provided.
 8. The switching chamberenclosure as claimed in claim 2, wherein an arcing chamber, a switchinggas damper and an arcing chamber cover are integrated in at least oneenclosure part.
 9. The switching chamber enclosure as claimed in claim3, wherein an arcing chamber, a switching gas damper and an arcingchamber cover are integrated in at least one enclosure part.
 10. Theswitching chamber enclosure as claimed in claim 2, wherein bearingshells for the switching shaft are integrated in the enclosure walls ofat least one of the enclosure parts.
 11. The switching chamber enclosureas claimed in claim 3, wherein bearing shells for the actuating shaftare integrated in the enclosure walls of at least one of the enclosureparts.
 12. The switching chamber enclosure as claimed in claim 4,wherein bearing shells for the actuating shaft are integrated in theenclosure walls of at least one of the enclosure parts.
 13. Theswitching chamber enclosure as claimed in claim 2, wherein outletopenings are provided in the separating joint for connecting rails to bepassed out.
 14. The switching chamber enclosure as claimed in claim 3,wherein outlet openings are provided in the separating joint forconnecting rails to be passed out.
 15. The switching chamber enclosureas claimed in claim 4, wherein outlet openings are provided in theseparating joint for connecting rails to be passed out.
 16. Theswitching chamber enclosure as claimed in claim 5, wherein outletopenings are provided in the separating joints for connecting rails tobe passed out.
 17. The switching chamber enclosure as claimed in claim2, wherein at least two enclosure parts are provided at ends of theswitching chamber enclosure and at least one intermediate enclosure partis provided.
 18. The switching chamber enclosure as claimed in claim 3,wherein at least two enclosure parts are provided at ends of theswitching chamber enclosure and at least one intermediate enclosure partis provided.
 19. The switching chamber enclosure as claimed in claim 4,wherein at least two enclosure parts are provided at ends of theswitching chamber enclosure and at least one intermediate enclosure partis provided.
 20. The switching chamber enclosure as claimed in claim 5,wherein at least two enclosure parts are provided at ends of theswitching chamber enclosure and at least one intermediate enclose partis provided.
 21. The switching chamber enclosure as claimed in claim 6,wherein at least two enclose parts are provided at ends of the switchingchamber enclosure and at least one intermediate enclosure part isprovided.